Devices are known in which thermal energy, absorbed from the sun's rays by a solar collector, is stored in a heat reservoir or tank connected through a heat pump to a thermal load such as a radiating element. Such a device has been described in U.S. Pat. No. 4,267,825 that also teaches the use of a pivoted heat pipe which in one angular position transmits heat from the collector to the reservoir and in another angular position allows the withdrawal of heat from the reservoir to the collector. Also known are devices in which incident sunlight is captured by a collapsible parabolic reflector for immediate utilization in a heater or cooker.